JP3034732B2 - METHOD AND APPARATUS FOR DISPLAYING 2D IMAGE OF DEFECTS IN METAL SHEET - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for displaying a two-dimensional image of an internal defect of a metal sheet detected by ultrasonic waves.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting an internal defect of a thin metal plate and performing two-dimensional image processing of its existence, for example, a C-scan ultrasonic wave disclosed in JP-A-61-151458 is disclosed. Generally, a flaw detection method is used. That is, the ultrasonic transmitter / receiver is set to 2 by an appropriate mechanical scanning mechanism.
While scanning two-dimensionally, the ultrasonic wave is transmitted in the thickness direction of the test material, and the reflected wave of the ultrasonic wave from the defect is detected. This is a method of displaying an image of an internal defect two-dimensionally, and is widely used industrially as an internal defect detection and display device for a thin metal plate.

[0003]

However, Japanese Patent Application Laid-Open No. 61-15 / 1986
In the method described in No. 1458, since the ultrasonic transmitter / receiver needs to be mechanically and two-dimensionally scanned, there is a disadvantage that it takes much time to display an image of an internal defect. For example, if the two-dimensional scanning method is XY scanning as shown in FIG. 6, the width of the test material is W, the length is L, the scanning speed of the ultrasonic transceiver is V, and the index length is I. At this time, even if the time required for the index is ignored, the time T ₀ required for image display is expressed by the following equation.

T ₀ = (L / I) × (W / V) (1) Therefore, for example, L = 400 mm, W = 250 mm, V = 200
Under the conditions of mm / sec and I = 1 mm, T ₀ = 500 sec, which is a calculation that takes approximately 10 minutes. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and provides a method and apparatus for displaying a two-dimensional image of a metal sheet internal defect, which can significantly reduce the time required for image display. The purpose is to do.

[0005]

According to a first aspect of the present invention, there is provided an image display method for detecting an internal defect in a thin metal sheet using ultrasonic waves. Transmitting in a direction and a plane perpendicular to the direction, and receiving a reflected wave from a defect; modulating the display luminance according to the amplitude of the received signal; and displaying the display position in accordance with the elapse of the reception time. The one-dimensional change in one direction (X direction) to display the time change of the received signal on a display as a luminance-modulated line; Intermittent by predetermined length relative to thin plate
To change the part for transmitting and receiving the plate wave ultrasonic wave, and move the display position of the received signal on the display in a direction (Y direction) orthogonal to the X direction according to the change. This is a method for displaying a two-dimensional image of a metal sheet internal defect.

A second aspect of the present invention is an image display apparatus for detecting an internal defect of a thin metal plate using ultrasonic waves. An ultrasonic transceiver that transmits in a plane created in the vertical direction, and receives a reflected wave from a defect, an ultrasonic receiver that amplifies a signal received by the ultrasonic transceiver, and an ultrasonic transceiver. The position is intermittent by a predetermined length relative to the metal sheet
A mechanism for moving the said display brightness by amplification of ultrasonic signal receiver has amplified is modulated, one-dimensionally scanned by the display position in the X-direction to display the received signal in accordance with the elapsed time of receipt, A display that moves a display position of a received signal in a Y direction orthogonal to the X direction in accordance with the relative movement between the ultrasonic transceiver and the metal sheet. It is a two-dimensional image display device.

[0007]

[Operation] The principle of the present invention will be described below.
The plate wave ultrasonic wave is typically transmitted to and received from the thin metal plate 1 by a tire-type ultrasonic probe 2 having a built-in ultrasonic vibrator 3, as shown in FIG. By changing the incident angle of the ultrasonic wave 41 transmitted from the ultrasonic transducer 3 to the thin metal plate 1, it is possible to transmit and receive the plate wave ultrasonic waves 42 in various modes. The ultrasonic wave 41 incident on the metal sheet 1 is converted into a plate wave ultrasonic wave 42, and propagates in a cross section formed by the thickness direction of the metal sheet 1 to be inspected and a direction perpendicular to the thickness direction. This is reflected and returned to the tire-type ultrasonic probe 2 as an echo and received.

Therefore, when the plate wave ultrasonic wave 42 is used, an internal defect of one entire cross section can be detected by one transmission / reception. At this time, the signal waveform with respect to time of the plate wave ultrasonic wave 42 received by the ultrasonic transducer 3 is as shown in FIG. That is, the signal waveform includes a transmission reverberation wave 43, a reflected wave 44 from an internal defect, a reflected wave 45 from a plate edge, and the like. Therefore, when displaying these signals on a display such as a CRT, the display brightness is modulated by the amplitude of the signals, and the display position is one-dimensionally scanned in one direction (X direction) according to the lapse of the reception time. It is possible to display the flaw detection result of one entire cross section as one scanning line subjected to luminance modulation.

Further, by moving the transmitting / receiving element of the plate wave ultrasonic wave 42 relatively to the metal sheet 1, the plate wave ultrasonic wave
By changing the part that transmits and receives 42 and moving the display position of the received signal on the display in the direction (Y direction) orthogonal to the X direction according to this change, a two-dimensional image display of the internal defect is possible. Becomes That is, according to the present invention, it is possible to obtain a two-dimensional image of the internal defect of the metal sheet simply by moving the transmitting / receiving element of the plate wave ultrasonic wave in one dimension relative to the metal sheet to be tested, The time required for forming a two-dimensional image can be greatly reduced.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example in which the present invention is used for displaying a two-dimensional image of an internal defect of a thin metal plate. In this figure, reference numeral 5 denotes a metal sheet 1 as a test material.
On which is placed. Reference numeral 6 denotes a scanning device that is supported by the support members 7 and 7 and that holds the tire-type ultrasonic probe 2 in a scanable manner. Reference numeral 8 denotes a signal generator that outputs an electric pulse, and 9 denotes an amplifier that amplifies the electric pulse. Reference numeral 10 denotes an ultrasonic receiver for amplifying a plate wave ultrasonic signal received by the ultrasonic transducer 3 of the tire-type ultrasonic probe 2, and reference numeral 11 denotes an A / D converter.

Reference numeral 12 denotes a two-dimensional image memory, which comprises, for example, a matrix of a plurality of memory elements 50 as shown in FIG. 2 and which can be independently addressed in two directions, that is, an X direction and a Y direction. Reference numeral 13 denotes a display such as a CRT for displaying the contents of the two-dimensional image memory 12;
This is a magnetic recording device that records the contents of the two-dimensional image memory 12.

Reference numeral 15 denotes a control device, which is the signal generator 8 described above.
Along with outputting a periodic synchronization signal to the A / D converter 11, controlling the storage of data output from the A / D converter 11 at a predetermined address in the two-dimensional image memory 12 and the magnetic recording device 14, Further, it controls functions such as performing scanning control of the tire-type ultrasonic probe 2. Then, upon receiving the periodic synchronization signal from the control device 15, the signal generator 8 outputs an impulse-like or burst-wave-like electric signal. The amplifier 9 amplifies the signal to a predetermined level and applies the signal to the ultrasonic transducer 3 built in the tire-type ultrasonic probe 2. The ultrasonic wave 41 transmitted from the ultrasonic vibrator 3 is transmitted as a plate wave ultrasonic wave 42 in a section formed by the thickness direction of the metal thin plate 1 as a test material and the direction perpendicular thereto, and the The reflected wave returns to the tire-type ultrasonic probe 2 and is received by the built-in ultrasonic transducer 3.

The received signal of the plate wave ultrasonic wave 42 is appropriately amplified by the ultrasonic wave receiver 10 and output to the A / D converter 11. The A / D converter 11 starts A / D conversion in response to a synchronization signal from the control device 15, A / D converts an input signal at a fixed sampling cycle for a fixed time, and converts a signal of the plate wave ultrasonic wave 42. Digitize and output. The two-dimensional image memory 12 writes the output digital signal at a predetermined address. One memory element 50 of the two-dimensional image memory 12
Is capable of storing, for example, 8-bit data, and the larger the amplitude of the signal of the plate wave ultrasonic wave 42 is, the larger numerical data is written to the two-dimensional image memory 12. This 2
The contents of the two-dimensional image memory 12 are always displayed on the display 13 via a D / A converter (not shown). At this time, the display luminance is proportional to the magnitude of the amplitude data of the plate wave ultrasonic wave 42 recorded in the two-dimensional image memory 12.

In the two-dimensional image display device having the internal defect constructed as described above, the plate wave ultrasonic wave 42 is intermittently sent by a predetermined length by the scanning signal from the control device 15 to transmit the plate wave ultrasonic wave 42. The received and transmitted signals are digitized and written to the two-dimensional image memory 12. At this time, the signal obtained by one transmission / reception of the plate wave ultrasonic wave 42 is written in the X direction of the two-dimensional image memory 12 with the passage of time, and the movement amount of the tire-type ultrasonic probe 2 with respect to the metal sheet 1 By shifting the writing position in the Y direction according to the above, a two-dimensional image of the internal defect of the metal sheet 1 is displayed on the display device 13. When a two-dimensional image display of the internal defect of one screen is obtained, the contents of the two-dimensional image memory 12 are stored in the magnetic recording device.
Recorded at 14.

Using this internal defect two-dimensional image display device, non-metallic inclusions in the steel plate having a thickness of 2.0 mm were detected. The obtained two-dimensional image is shown in the sketch diagram of FIG. This figure is obtained by transmitting and receiving sheet wave ultrasonic waves in a direction perpendicular to the rolling direction of the steel sheet. In addition, what was shown as a through-hole in the figure is a 1mm
It is a drill hole of φ.

As can be seen from this figure, the portion where the amplitude of the reflected wave of the plate wave ultrasonic wave is higher is displayed in darker black, and H32A to H3
Non-metallic inclusions indicated by 2J are clearly detected. In addition, the direction shown by L in the figure is the rolling direction of the steel sheet, and the direction shown by C is a direction perpendicular to the rolling direction L of the steel sheet. In conventional C-scan ultrasonic testing, it took about 500 seconds to obtain a two-dimensional image of this inclusion, but the time required for two-dimensional image formation with the apparatus of the present invention was only four seconds. However, the time was reduced by more than 100 times.

In the above embodiment, the tire-type ultrasonic probe is used for transmitting and receiving the plate wave ultrasonic wave. However, the present invention is not limited to this, and the ultrasonic wave capable of transmitting and receiving the plate wave ultrasonic wave is used. Any type of transmitter / receiver can be used. Further, the embodiment of the present invention is not limited to the above-described embodiment. For example, a transmitter / receiver for a plate wave ultrasonic wave is installed on a line through which a metal thin plate passes, and the transmitter / receiver for a plate wave ultrasonic wave is transported by the metal thin plate. And the metal sheet may be relatively moved.

[0018]

As described above, according to the present invention, it is possible to obtain a two-dimensional image of an internal defect in a metal sheet in a very short time, which is effective for quality control and its assurance in the production of a metal sheet. It can be used, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a two-dimensional image memory used in the present invention.

FIG. 3 is a diagram showing a sketch of a two-dimensional image of an internal defect obtained when the apparatus of the present invention is applied to a steel plate.

FIG. 4 is a cross-sectional view illustrating the principle of transmission and reception of plate wave ultrasonic waves.

FIG. 5 is a characteristic diagram showing signal waveforms in transmission and reception of plate wave ultrasonic waves.

FIG. 6 is an explanatory diagram of a scanning method of an ultrasonic probe by a conventional C-scan ultrasonic flaw detection method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal thin plate 2 tire-type ultrasonic probe (ultrasonic transmitter / receiver) 3 ultrasonic transducer 6 scanning device 8 signal generator 9 amplifier 10 ultrasonic receiver 11 A / D converter 12 two-dimensional image memory 13 display 14 Magnetic recording device 15 Control device 41 Ultrasonic wave 42 Plate wave ultrasonic wave 50 Memory element

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (2)

(57) [Claims] 1. An image display method for detecting an internal defect of a metal sheet using ultrasonic waves, wherein a sheet wave ultrasonic wave is transmitted in a plane formed in a thickness direction of the metal sheet and in a direction perpendicular to the thickness direction. Receiving the reflected wave from the defect, and modulating the display luminance according to the amplitude of the received signal, and changing the display position in one direction (X direction) according to the elapse of the reception time.
The by varying one-dimensionally, relatively predetermined and displaying on the display as a time varying intensity modulated line of the received signal, the position of the plate wave ultrasonic transmitting and receiving element to the metal sheet A step of intermittently moving by a length to change a portion for transmitting and receiving a plate wave ultrasonic wave and moving a display position of a received signal on a display in a direction orthogonal to the X direction (Y direction) according to the change; A method for displaying a two-dimensional image of a defect inside a metal sheet, comprising: 2. An image display device for detecting an internal defect of a metal sheet using ultrasonic waves, wherein the sheet wave ultrasonic waves are transmitted in a plane formed in a thickness direction of the metal sheet and in a direction perpendicular to the thickness direction. And an ultrasonic transceiver that receives a reflected wave from a defect, an ultrasonic receiver that amplifies a signal received by the ultrasonic transceiver, and a position of the ultrasonic transceiver that is relative to a thin metal plate. To
A mechanism for intermittently moving by a predetermined length, and a display brightness is modulated by amplification of a signal amplified by the ultrasonic receiver, and a display position is one-dimensionally scanned in the X direction according to elapse of a reception time and received. A display for displaying a signal and moving a display position of a received signal in a Y direction orthogonal to the X direction in accordance with the relative movement of the ultrasonic transceiver and the metal thin plate. Internal defect 2
Dimensional image display device.